The present invention relates to building materials, and more specifically composite lightweight building panels which can be interconnected to build structures such as modular buildings.
Due to the high cost of traditional building materials and the extensive transportation and labor costs associated therein, there is a significant need in the construction industry to provide a lightweight, precast, composite building panel which may be transported to a building site and assembled to provide a structure with superior strength and insulative properties. Previous attempts to provide these types of materials have failed due to the extensive transportation costs and the low insulative values associated with prefabricated concrete and wire products. Further, due to the brittle nature of concrete, many of these types of building panels become cracked and damaged during transportation.
More specifically, the relatively large weight per square foot of previous building panels has resulted in high expenses arising not only from the amount of materials needed for fabrication, but also the cost of transporting and erecting the modules. Module weight also placed effective limits on the height of structures, such as stacked modules, e.g. due to limitations on the total weight carried by the lowermost modules. Furthermore, there is substantial fabrication labor expense that can arise from efforts needed to position, design and construct molds, and the materials and labor costs involved in providing and placing reinforcement materials. Accordingly, it would be useful to provide a system for modular construction which is relatively light, can be readily stacked to heights greater than in previous configurations and, preferably, inexpensive to design and use.
Further, in many situations panels or modules are situated in locations where it is desirable to have openings therethrough to accommodate doorways, windows, cables, pipes and the like. In some previous approaches, panels were required to be specially designed and cast so as to include any necessary openings, requiring careful planning and design and increasing costs due to the special, non-standard configuration of such panels. In other approaches, panels were cast without such openings and the openings were formed after casting e.g. by drilling or similar procedures. Such post-casting procedures as drilling, particularly through the relatively thick and/or steel-reinforced panels as described above, was a relatively labor-intensive and expensive process. In many processes for creating openings, there was a relatively high potential for cracking or splitting of a panel or module. Accordingly, it would be useful to provide a module which can be easily provided with openings such as doors and windows in desired locations and with a reduced potential for cracking or splitting.
One example of a composite building panel which attempts to resolve these problems with modular panel construction is described in U.S. Pat. No. 6,202,375 to Kleinschmidt (the ""375 patent). In this invention, a building system is provided which utilizes an insulative core with an interior and exterior sheet of concrete and which is held together with a metallic wire mesh positioned on both sides of an insulative core. The wire mesh is embedded in concrete, and held together by a plurality of metallic wires extending through said insulative core at a right angle to the longitudinal plane of the insulative core and concrete panels. Although providing an advantage over homogenous concrete panels, the composite panel disclosed in the ""375 patent does not provide the necessary strength and flexure properties required during transportation and high wind applications. Further, the metallic wire mesh materials are susceptible to corrosion when exposed to water during fabrication, and have poor insulative qualities due to the high heat transfer qualities of metallic wire. Thus, the panels disclosed in the ""375 patent may eventually fail when various stresses are applied to the building panel during transportation, assembly or subsequent use. Furthermore, these panels have poor insulative qualities in cold climates due to the high heat transfer associated with the metallic wires.
Other attempts have been made to use improved building materials that incorporate carbon fiber. One example is described in U.S. Pat. No. 6,230,465 to Messenger, et al. which utilizes carbon fiber in combination with a steel reinforced precast frame with concrete. Unfortunately, the insulative properties are relatively poor due to the physical nature of the concrete and steel, as well as the excessive weight and inherent problems associated with transportation, stacking, etc.
Accordingly, there is a significant need in the construction and building industry to provide a composite building panel which may be used in modular construction and which is lightweight, provides superior strength and has high insulative values. Further, a method of making these types of building panels is needed which is inexpensive, utilizes commonly known manufacturing equipment, and which can be used to mass produce building panels for use in the modular construction of temporary shelters, permanent housing, hotels, and other buildings.
It is thus one aspect of the present invention to provide a composite wall panel which has superior strength, high insulating properties, is lightweight for transportation and stacking purposes and is cost effective to manufacture. Thus, in one embodiment of the present invention, a substantially planar insulative core with interior and exterior surfaces is positioned between concrete panels which are reinforced with carbon fiber grids positioned substantially adjacent the insulative core and which is interconnected to a plurality of diagonal carbon fiber strands. In a preferred embodiment of the present invention, the interior layer of concrete is comprised of a low-density concrete.
It is yet another aspect of the present invention to provide a superior strength composite wall panel which utilizes carbon fiber materials which are oriented in a novel geometric configuration which interconnects the insulative core and both the interior and exterior concrete panels. In one embodiment of the present invention, a plurality of carbon fibers are oriented in a substantially diagonal orientation through the insulative core and which are operably interconnected to carbon fiber mesh grids positioned proximate to the interior and exterior surfaces of the insulative core and which operably interconnect both the interior and exterior concrete panels to the insulative core. Preferably, the carbon fiber mesh grid is comprised of a plurality of first carbon fiber strands extending in a first direction which are operably interconnected to a plurality of second carbon fiber strands oriented in a second direction. Preferably, the carbon fiber mesh grids are embedded within the interior and exterior concrete panels.
It is a further aspect of the present invention to provide a composite wall panel with an insulative core which has superior compressive strength and which utilizes STYROFOAM(copyright), a ridged, light-weight expanded polystyrene (xe2x80x9cEPSxe2x80x9d) material, or other similar materials. Thus, in another aspect of the present invention, a plurality of anti-compression pins are placed throughout the insulative core and which extend substantially between the interior and exterior surfaces of the insulative core. Preferably, these pins are comprised of ceramic, fiberglass, carbon-fiber or other materials which are resistant to compression and do not readily transfer heat.
It is another aspect of the present invention to provide a composite wall panel which can be easily modified to accept any number of exterior textures, surfaces or cladding materials for use in a plurality of applications. Thus, the present invention is capable of being finished with a brick surface, stucco, siding and any other type of exterior surface. In one embodiment of the present invention, a paraffin protective covering is provided on the exterior surface for protection of the exterior surface during manufacturing. The paraffin additionally prevents an excessive bond between the individual bricks and exterior concrete wall to allow the removal of a cracked or damaged brick and additionally has been found to reduce cracking in the bricks due to the differential shrinkage of the exterior concrete layer and clay brick. Furthermore, other types of materials such as drywall and other interior finishes can be applied to the interior concrete panel as necessary for any given application.
It is yet a further aspect of the present invention to provide a novel brick configuration which allows broken or cracked bricks to be quickly and effectively replaced. Thus, in one embodiment of the present invention a beveled brick design is provided wherein a rear portion of the brick has a greater diameter than a front end, and is embedded into the exterior concrete layer during the forming process. This design provides superior strength, and allows a damaged brick to be chiseled free and quickly replaced with a new brick by applying a glue or epoxy material.
It is yet another aspect of the present invention to provide a composite modular wall panel which can be used to quickly and efficiently construct modular buildings and temporary shelters and is designed to be completely functional with regard to electrical wiring and other utilities such as telephone lines, etc. Thus, the present invention in one embodiment includes at least one utility line which may be positioned at least partially within the composite wall panel and which accepts substantially any type of utility line which may be required in residential or commercial construction, and which can be quickly interconnected to exterior service lines. This utility line may be oriented in one or more directions and positioned either near the interior concrete panel, exterior concrete panel, or both.
Thus, in one embodiment of the present invention, a composite wall panel is provided which comprises:
an insulative core having an interior surface and an exterior surface;
a substantially impermeable vapor barrier positioned adjacent to said insulative core;
a first carbon fiber grid positioned proximate to said exterior surface of said insulative core and comprising a plurality of first carbon fibers oriented in a first direction which are operably interconnected to a plurality of second carbon fibers oriented in a second direction;
a second carbon fiber grid positioned proximate to said interior surface of said insulative core and comprising a plurality of first carbon fibers oriented in a first direction which are operably interconnected to a plurality of second carbon fibers oriented in a second direction;
a plurality of carbon fiber strands operably interconnecting said first carbon fiber grid and said second carbon fiber grid and extending through said insulative core in a substantially diagonal orientation;
an exterior layer of concrete positioned substantially adjacent to said exterior surface of said insulative core;
an interior layer of concrete positioned substantially adjacent to said interior surface of said insulative core, wherein said insulative core, said exterior layer of concrete, said interior layer of concrete, said first carbon fiber grid and said second carbon fiber grid are operably interconnected with said plurality of carbon fiber strands.